Method of making insulating-coverings for electric conductors.



eteran s rens PATENT onrion.

WILLIAIVLALFRED PHILLEPS AND FREDERICK HUTCHINS, OF LONDGN, ENGLAND.

METHOD OF MAKING INSULATING-COVERINGS FOR ELECTRIC CONDUCTQRS.

N 0 Drawing.

To all whom it may concern:

Be it known that we, \Vrnmmt Anrnnn P nnnirs and FREDERICK Iiu'rcmxs, subjects ofthe King of England, and residing in London, have invented certain new and useful Improvements in Methods of Making l nsnlsiting-Coverings for Electric Conductors, of which the followingis a specification This invention relates. to improvements in the insulation of electric conductors and compounds therefor, and has particular reference to a compound which forms an enameled covering upon the conductor, such covering being hard, tough and flexible and having good insulating properties.

According to this invention aninsulating covering of enamel is produced upon an. electrical conductor, by first coating the con ductor with a mixture comprising the material commonly known as gilsonite and castor oil with or without linseed oil, and the coated conductor is subsequently subjccted to a heating process of a duration and intensity sufficient to drive off the vole tile constituents of the compound and con-- vert the coating into a hard tough and tlexible enamel. The substance renerred to as gilsonite is sometin'ies called gilsonite asphaltum or uintate, and although it belongs tothe asph'altum group of mineral subtan'ces, an enamel coating of a gilsonite compound according to this invention is found to possess properties as an insulating" covering superior to those-of a covering made, say, from ordinary asphaltum or bitumen.

One method of preparing the con'ipound for use according to this invention is as follows :-Two parts by weight of gilsonite are mixed with three of castor oil, and the mixture is heated until it is reduced by about 15 per cent. of its weight. This stage of the process is convenientlyaccelerated and facilitated by forcing air through the mixture during heating. If air be thus used the necessary reduction in Weight can be effected in about three hours. The resulting compound when cool is mixed with a suitable quantity of paraflin oil or similar hydrocarbon so as to give a specific gravity of, say, 0.840 at 38, centigrade.

Another form of the-compound may be made by mixing equal parts by weight of gilsonite, castor oil and linseed oil, and by preparing the mixture in the way above mentioned.

Specification of Letters Patent. Patented; N 30, 909- Application filed June 8, 1968. Serial No. 437,354. V

The wire .to beenameled is passed through a bath of the mixture, the bath being kept at a temperature of about 38* centigrade. The wire is then drawn at a suitable speed varying, say, from 15'to 6L0 ft. per ninute according to the size of the wire, through a heated tube or chamber, wherein the wire is subjected to a'tei'npcrature sufficiently high to drive off the volatile constituents of the compound, leaving on the wire an enamel coating. This heated tube may be of any convenientlength so that the wire in its passage through it is subjected to the proper temperature for a sufliciently long time. The'process of coating may be repeated, the wire being passed several times through the bath and the heated tube before being wound on to a drum or otherwise prepared for storage.

It is to be understood that the proportions mentioned above are merely given by way of example, and that. they may be v: ried, and further that the amount of the preliminary treatment, the specific gravity of the coating-compound, the temperature of the heated tube andthe speed of the wire may likewise be varied.

. hat. we claim as our invention and desire to secure by Letters Patent is 1. The herein described method of making an insulating covering for electric conductors, which consists in mixing gilsonite and castor oil in the approximate proportions of two parts by weight of gilsonite to three parts of ca'stor oil,'heating the mixture until it is reduced by aboutl5j4) of its weight, allowing it to cool and mixing it with a hydrocarbon in such proportion as to give a specific gravity of approximately .840 at 38 C., substantially as set forth.

2. The herein described method of making an'insulating covering for electric c onductors; which consists in mixing gilsonite and castor oil inthe approximate proportions of two parts by weight of; gilsonite ,to three parts of castor oil, heating the mixture and forcing air through it until it is reduced by .about 15% of its Weight, alloWingitto cool and mixing it with a hydrocarbon in such proportion as to give a specific gravity of approximately .840 at 38 0., substantially as described.

3. The herein described method of making an insulating covering for electric conductors, which consists in mixing approximately equal parts of g1lson1te, castor 011 and 1111- seed oil, heating the mixture until it is reduced by about 15% of its weight, allowing it to cool and mixing it With a'hydroczn'bon in such proportion 21's to give a specific gravity of approximately .840 at 38 (1., substantially as set forth.

4. The herein described method of making an insulating eovering for electric conductors, Which consists in mixing approximately equal parts of gilsonite, castor oil and linseed oil, heating the mixture an forcing air through it until it is reduced by about 15% of its weight, allowing it to cool and mixing it with a hydroezn'bon in such proportion as to give :1 speci .840 at 58 (3., substantially as set forth.

to gravity of approximately v15 In testimony whereof We have signed our names to this specification in the presence of two subscribing Witnesses. 

